The invention relates to motor vehicles in general, and more particularly to improvements in methods of and in apparatus for analyzing and evaluating exhaust gases of motor vehicles. Still more particularly, the invention relates to improvements in methods of and in apparatus for analyzing and evaluating exhaust gases of motor vehicles wherein the exhaust pipe contains a three-way catalytic converter downstream of a lambda sensor.
It is already known to sample the exhaust gases by resorting to a so-called ASU measurement which involves a determination of the HC and/or CO content of exhaust gases issuing from the exhaust pipe of a standing (idling) motor vehicle. A drawback of such procedure is that signals which are generated by the sampling means do not furnish sufficient information to complete an accurate evaluation of exhaust gases.
Detection of certain poisonous ingredients, such as nitrogen oxide, is possible only when the motor vehicle is in motion and is under load. Thus, such sampling of exhaust gases in accordance with heretofore known proposals necessitates the utilization of a complex and expensive roller bench.
It was further proposed to subject exhaust gases to a more elaborate analysis by running, for a predetermined interval of time, the engine of a motor vehicle which is supported by a roller type dynamometer, also called roller bench or test stand. Gases which issue from the exhaust pipe are mixed with filtered atmospheric air at a constant ratio, and a portion of the thus obtained mixture is collected in bags for subsequent determination of the concentration of toxic and/or other undesirable ingredients. A drawback of such proposal is that the testing involves the utilization of a test stand as well as of complex and expensive evaluating instruments and apparatus. Therefore, such methods can be practiced only by a few large or giant organizations which can afford the necessary apparatus including test stands and other costly equipment.
The article by Schurmann and Staab on pages 35-39 of Motortechnische Zeitschrift 48 (1987) entitled "Measurements of the Exhaust Mass Emissions in Vehicles on the Road" describes a prototype which was built into a Volkswagen vehicle and wherein the exhaust gases must be mixed with air prior to passing through a condensate separator and a filter which forms part of an exhaust gas processing unit. A computer evaluates the signals which are supplied by the processing unit, and the computer further receives signals from a fuel flow meter and a speedometer.
U.S. Pat. No. 4,782,690 to Terasaka discloses an air/fuel ratio detecting apparatus and a method of detecting an abnormal condition of the apparatus.
U.S. Pat. No. 4,441,359 to Ezoe discloses a method of and an apparatus for testing vehicles. The apparatus employs an exhaust gas tester which samples gases at the discharge end of the exhaust pipe and transmits signals to a central control device employing a programmable microcomputer.
Published European patent application No. 0 096 514 of Parker discloses a detector of combustible or combustion-supporting constituents of exhaust gases which issue from internal combustion engines.
Published German patent application No. 29 51 316 of Bozon et al. discloses a catalytic filter for purification of exhaust gases issuing from diesel engines.
Published German patent application No. 38 09 082 of Klingenberg discloses an apparatus for simultaneous analysis of several samples of exhaust gases. The exhaust gases are withdrawn upstream and downstream of a catalytic converter and are conveyed to a single analyzing unit by way of a single multi-way valve.
Published German patent application No. 32 32 416 of Kraft et al. discloses a data gathering and processing system for use in motor vehicles. The system is designed to cyclically receive data from a plurality of monitoring devices, and the processed information can be displayed or printed.
Published German patent application No. 34 38 172 of Marte Electronic discloses an exhaust gas evaluating apparatus which employs a sensor serving to ascertain and to display typical emission values. The sensor cooperates with a data adapter which transmits to a memory data pertaining to typical emission values.
Published European patent application No. 0 239 744 of Siemens discloses a sensor and a method of cleaning conduits for flue gases.
Published German patent application No. 2 304 464 of Neidhard et al. discloses a sensor which is designed to monitor the operativeness of catalytic converters in detoxicating units for exhaust gases.
East German Pat. No. 269 673 to Heinze et al. discloses an apparatus for and a method of testing oxidative catalytic converters.
Published German patent application No. 27 52 862 of Gruden discloses a method of testing exhaust gases which issue from an internal combustion engine. The method involves ascertaining the timing of ignition during idling, a monitoring of the so-called air number lambda during idling, and at least one monitoring of the air number lambda at rotational speeds along the zero load line.
Published German patent application No. 26 43 739 of Vossner" discloses a method of monitoring the operation of catalytic converters in exhaust pipes. The method is practiced by employing two temperature sensors serving to generate signals when the catalytic converter is no longer capable of performing its function.
Published German patent application No. 35 16 981 of Vrang et al. discloses a method which is similar to or identical with the method of Vossner.
Published German patent application No. 37 36 259 of Kluczynski discloses a motor vehicle with an electronic control unit which can be switched from normal operation to determination of the degree of convertibility of a catalytic converter in the exhaust pipe of the vehicle.
Published German patent application No. 35 34 033 of Chassiotis discloses a method of ascertaining the fuel consumption and the percentage of emission of toxic products by an Otto engine. The inventor relies upon a specific formula. The concentration of toxic ingredients in exhaust gases is measured while the engine is idling at a lower RPM and at a higher RPM.
Published German patent application No. 31 44 349 of Melzer discloses an adjustable soot combusting unit for use in the exhaust system of a diesel engine.